EP3176875A1 - Active antenna architecture with reconfigurable hybrid beam formation - Google Patents

Abstract

The antenna architecture comprises a hybrid beamformer consisting of, on the one hand, Ny stacked quasi-optical beamformers, each quasi-optical beamformer having a parallel plate waveguide provided with a radiating aperture linear and incorporating a lens (13) and internal horns provided with beam access ports, each quasi-optical beamformer being able to form beams in two transmission and reception frequency bands, in a first direction space, and on the other hand, at least one electron beam trainer comprising a combination device (34) connected to Nx phase and amplitude control chains, each phase and phase control chain. amplitude being connected to a respective beam access port of each quasi-optical beamformer, the electron beamformer being adapted to form beams in a second direction of space, orthogonal to the first direction.

Description

The present invention relates to a reconfigurable hybrid beam-forming active antenna architecture. The antenna can be applied to the terrestrial or space domain and in particular in the field of satellite telecommunications. In particular, it can be mounted on a terrestrial terminal or on board a satellite.

To facilitate the description, the mode of operation of the beamformers is assumed in reception, but a similar description could be formulated in transmission.

An electron beam-forming reconfigurable active antenna has a plurality of radiating elements, active chains for processing the signals received by the radiating elements, and a beamformer that recombines the received signals coherently in different directions to form different beams. . Each radiating element is connected to the beamformer via a dedicated active channel. When the formation of beams is carried out on microwave signals, the processing carried out by each active channel comprises a filtering and an amplification of the received signals. When the beam formation is carried out on analog signals transposed in baseband, the processing carried out by each active chain further comprises a transposition in frequency. Treatments may also include scanning if the beam formation is performed on digitized signals.

Classically, as represented on the example of the figure 1 , a planar radiofrequency beamformer divides the signals received by each radiating element E1, E2,..., Ei,..., EN, into M sub-signals which are conveyed in M different channels, then applies to each of the M sub-signals, a phase shift and a controllable value attenuation before recombining the sub-signals from the N radiating elements to form M different beams S1, S2, ..., SM, also called spots. However, the radiofrequency planar beamformer requires crossings between the channels carrying the sub-signals, the number of crossings being equal to the product between the number M of beams and the number N of radiating elements. Consequently, the larger the number of beams to be made, the greater the mass, the size and the complexity of this beamformer. This beamformer therefore quickly becomes impractical when a large number of beams have to be made to cover a wide angular sector.

When beamforming is performed on analog signals transposed into baseband, crossovers are easier to achieve using ASICs. This limits the weight and bulk of the beamformer, but this technology leads to excessive power consumption.

When beamforming is performed on digital signals, the digitization of the signals on a large number of radiating elements generally leads to large consumed power.

According to another technology, there are planar quasi-optical beamformers using electromagnetic propagation of radiofrequency waves from several input power sources, for example internal horns, according to a propagation mode in general TEM (in English). : Transverse Electric Magnetic) between two parallel metal plates (in English: parallel plates). The focusing and the collimation of the beams can be carried out by a lens, for example an optical lens as described in particular in the documents US 3170158 and US 5936588 which illustrate the case of a Rotman lens, the lens being inserted in the path of propagation of radio waves, between the two parallel metal plates. Different types of lenses can be used, these lenses being essentially phase correctors and allowing in most cases to convert one or more cylindrical waves emitted by the sources into one or more plane waves propagating in the waveguide. wave with parallel metal plates. The lens may comprise two opposite edges with parabolic profiles, respectively input and output. Alternatively, the lens may be a dielectric lens, or a gradient index lens, or any other type of lens. As this technology uses parallel plate waveguides, As an alternative to using a plurality of discrete radiators aligned side by side, it is possible to use a continuous linear radiating aperture at the output of each parallel plate waveguide. These linear radiating apertures, which are not spatially quantized, have much higher performances compared to the linear arrays of several radiating elements, for the depointed beams, because of the absence of quantization, and in bandwidth because of the absence of resonant propagation modes.

A quasi-optical beamformer is much simpler than traditional waveguide beamformers because it has no couplers or crossover devices and allows for multiple beams that cover a wide angular sector without no aberration. In addition, their bandwidth is very important and they can operate both in an Rx transmit band and in a Tx receive band. However, known planar beam formers are only able to form beams in one dimension of space, in a direction parallel to the plane of the metal plates. To form beams according to two dimensions of the space, in two directions, respectively parallel and orthogonal to the plane of the metal plates, it is necessary to combine orthogonally between them, two sets of beam forming, each beam forming assembly consisting of a stack of several layers of unidirectional beamformers. To orthogonally combine two sets of beam forming, it is further necessary to arrange connection interfaces, in particular input / output connectors, on each set of beam forming and then connect in pairs the different inputs and outputs. corresponding outputs of the two sets of beam forming by dedicated interconnection cables as shown for example in the document US 5,936,588 for lens bundle trainers. This architecture is satisfactory for the formation of a small number of beams, but becomes very complex and too much space when the number of beams increases.

There is no planar beam forming device for forming beams in two dimensions of space. By Moreover, there are also no simple solutions for interconnecting two unidirectional beamformers to overcome connection interfaces and interconnection cables.

The object of the invention is to provide a novel reconfigurable active antenna architecture comprising a simpler electronic beamformator than the known electron beam formers, making it possible to reduce the number of signals to be controlled in phase and amplitude, to reduce the number of signals to recombine electronically for each beam, and to make a large number of beams from a large number of radiating elements.

• de Ny formateurs de faisceaux quasi-optiques planaires empilés, où Ny est un nombre entier supérieur à un, chaque formateur de faisceaux quasi-optique comportant un guide d'onde à plaques parallèles ayant deux extrémités respectivement munies d'une ouverture rayonnante linéaire et de My ports d'accès de faisceaux, une lentille intégrée dans le guide d'onde à plaques parallèles, des cornets internes distribués périodiquement côte à côte le long d'un axe focal de la lentille, les ports d'accès de faisceaux étant respectivement associés aux cornets internes, chaque formateur de faisceaux quasi-optique étant apte à former des faisceaux dans deux bandes de fréquences séparées, respectivement d'émission et de réception, selon une première direction de l'espace parallèle au plan des guides d'ondes à plaques parallèles, et d'autre part,
• d'au moins un formateur de faisceaux électronique planaire comportant Ny chaînes de contrôle de phase et d'amplitude et un dispositif de combinaison comportant Ny entrées respectivement reliées aux Ny chaînes de contrôle de phase et d'amplitude et au moins une sortie de faisceaux chaque chaîne de contrôle de phase et d'amplitude étant connectée à un port d'accès de faisceaux respectif de chaque formateur de faisceaux quasi-optique, le formateur de faisceaux électronique étant apte à former des faisceaux selon une deuxième direction de l'espace, orthogonale à la première direction.

For this purpose, the invention relates to a reconfigurable active beam-forming antenna architecture, comprising a hybrid beamformer constituted on the one hand,

• of Ny planar quasi-optical stacked beam formers, where Ny is an integer greater than one, each quasi-optical beamformer having a parallel plate waveguide having two ends respectively provided with a linear aperture and My beam access ports, a lens integrated in the parallel plate waveguide, internal horns periodically distributed side by side along a focal axis of the lens, the beam access ports being respectively associated to the internal cones, each quasi-optical beamformer being able to form beams in two separate frequency bands, respectively transmitting and receiving, in a first direction of the space parallel to the plane of the plate waveguides parallel, and on the other hand,
• at least one planar electron beamformer comprising Ny phase and amplitude control strings and a combination device having Ny inputs respectively connected to the Ny phase and amplitude control strings and at least one beam output each phase and amplitude control chain being connected to a respective beam access port of each quasi-optical beamformer, the electron beamformer being adapted to form beams in a second orthogonal space direction in the first direction.

Advantageously, the antenna architecture may further include switches capable of selecting, in each quasi-optical beamformer, a port among all the available beam access ports, each switch having an input connected to a transmission channel. phase and amplitude control of the electron beamformer and several outputs respectively connected to a plurality of respective beam access ports of the corresponding quasi-optical beamformer.

Advantageously, the beam access ports may consist of a first row of transmission ports arranged side by side along the focal axis of the lens and a second row of reception ports arranged side by side. along the focal axis of the lens, the first and second rows being stacked one above the other, the transmitting ports and the receiving ports being distinct and of different sizes, each port of emission, respectively receiving, being provided with a respective filter centered on the transmission frequency band, respectively receiving.

Advantageously, the linear radiating openings of the different quasi-optical beam formers can be networked to a single, partially reflective radome, common to all quasi-optical beamformers, the radome having a first partially reflecting surface sized for the sub-reflector. receiving frequency band and a second partially reflecting surface sized for the transmitting frequency subband, the first and second partially reflecting surfaces being respectively disposed at the output of the linear radiating apertures at a distance corresponding to a wavelength each of the two transmitting and receiving frequency sub-bands.

Advantageously, the hybrid beamformer may comprise a quasi-optical beamformer common to the Tx transmission and the Rx reception, two separate specific electron beam formers, respectively dedicated to transmission and reception, and switches having different positions respectively capable of selecting one of a plurality of beam access ports, each switch selectively connecting, depending on its position, a phase and amplitude control chain of the electron beamformer dedicated to the transmission, respectively to the receiving, at one of the transmitting or receiving ports, each quasi-optical beamformer.

Advantageously, the beam access ports, selected by the switches in all stacked quasi-optical beam formers and connected to the same electron beam trainer, can have an identical direction of orientation and cover an identical geographic area.

Alternatively, a first portion of the beam access ports, selected by the switches in the stacked quasi-optical beamformers, may cover a first geographic area and a second portion of the beam access ports, selected by the switches in stacked quasi-optical beam trainers may cover a second geographic area adjacent to the first geographic area.

Advantageously, the combination device may consist of a combiner / divider comprising Nx inputs respectively connected to the Nx phase and amplitude control strings and a beam output.

Advantageously, the combination device may comprise a shunt for splitting each phase and amplitude control chain into several different channels, each channel comprising a dedicated phase shifter.

Advantageously, the combination device may consist of a quasi-optical beamformator in PCB technology comprising Nx inputs respectively connected to Nx channels of phase and amplitude control and several beam outputs.

• figure 1 : un schéma synoptique d'un exemple de formateur de faisceaux électronique, selon l'art antérieur ;
• figure 2 : un schéma synoptique, en vue de côté, d'un exemple de formateur de faisceaux hybride multifaisceaux, selon l'invention;
• figure 3 : un schéma, en perspective, de quatre formateurs de faisceaux quasi-optiques empilés, selon l'invention ;
• figure 4 : un schéma, en vue de dessus, d'un formateur de faisceaux quasi-optique, selon l'invention ;
• figure 5 : un schéma synoptique partiel d'un exemple de formateur de faisceaux hybride dans lequel les fonctions des formateurs de faisceaux électroniques sont détaillées, selon l'invention ;
• figures 6a, 6b, 6c: trois schémas, respectivement en coupe longitudinale, en vue de dessus et en vue de dessous, d'un formateur de faisceaux quasi-optique comportant des ports dédiés à la réception Rx et des ports dédiés à l'émission Tx, selon l'invention ;
• figure 7 : une vue en coupe longitudinale, d'un exemple de trois formateurs de faisceaux quasi-optiques empilés munis d'un radome commun équipé de deux surfaces partiellement réfléchissantes, selon l'invention ;
• figure 8a : architecture d'antenne pour un terminal utilisateur asservi sur un satellite, apte à former un faisceau d'émission et un faisceau de réception avec sélection de la direction d'orientation du faisceau, selon l'invention ;
• figure 8b : un exemple de faisceaux formés par le formateur de faisceaux hybride, dans le cas de la sélection, dans deux formateurs de faisceaux quasi- optiques adjacents, de ports d'accès de faisceaux couvrant des secteurs géographiques adjacents, selon l'invention ;
• figure 9 : architecture d'antenne multifaisceaux d'émission et de réception avec sélection de la direction d'orientation des faisceaux, dans le cas où les faisceaux couvrent un secteur géographique prédéterminé, selon l'invention ;
• figure 10 : architecture d'antenne multifaisceaux d'émission et de réception avec sélection de la direction d'orientation des faisceaux, dans le cas où chaque formateur de faisceaux électronique comporte plusieurs voies de déphasage différentes, selon l'invention ;
• figure 11 : architecture d'antenne multifaisceaux d'émission et de réception avec sélection de la direction d'orientation des faisceaux, dans le cas où chaque formateur de faisceaux électronique comporte un formateur de faisceaux quasi-optique en technologie PCB, selon l'invention.

Other features and advantages of the invention will become clear in the following description given by way of purely illustrative and non-limiting example, with reference to the attached schematic drawings which represent:

• figure 1 : a block diagram of an example of electron beam trainer, according to the prior art;
• figure 2 : a block diagram, in side view, of an example of multibeam hybrid beamformer according to the invention;
• figure 3 : a diagram, in perspective, of four stacked quasi-optical beam formers, according to the invention;
• figure 4 : a diagram, in plan view, of a quasi-optical beamformer, according to the invention;
• figure 5 : a partial block diagram of an example of a hybrid beamformer in which the functions of the electron beam formers are detailed, according to the invention;
• Figures 6a , 6b, 6c three diagrams, respectively in longitudinal section, in plan view and in bottom view, of a quasi-optical beamformer comprising ports dedicated to reception Rx and ports dedicated to the transmission Tx, according to the invention ;
• figure 7 : a longitudinal sectional view of an example of three stacked quasi-optical beam formers provided with a common radome equipped with two partially reflecting surfaces, according to the invention;
• figure 8a antenna architecture for a user terminal slaved to a satellite, adapted to form a transmission beam and a reception beam with selection of the direction of beam orientation, according to the invention;
• figure 8b an example of beams formed by the hybrid beamformer, in the case of selection, in two adjacent quasi-optical beam formers, beam access ports covering adjacent geographical areas, according to the invention;
• figure 9 : multibeam transmission and reception antenna architecture with selection of the direction of orientation of the beams, in the case where the beams cover a predetermined geographical area, according to the invention;
• figure 10 : multibeam transmission and reception antenna architecture with selection of the direction of beam orientation, in the case where each electron beam trainer comprises several different phase shift channels, according to the invention;
• figure 11 : multibeam transmission and reception antenna architecture with selection of the direction of beam orientation, in the case where each electron beam trainer comprises a quasi-optical beamformator PCB technology, according to the invention.

The novel reconfigurable beam forming active antenna architecture according to the invention comprises a hybrid beamformer consisting of at least two planar quasi-optical beamformers stacked one above the other, and at least one planar electron beamformer connected to a respective port of each planar quasi-optical beamformer. Each quasi-optical beamformer is capable of forming beams in a first direction of the space parallel to the plane of the quasi-optical beamformer. The electron beamformer is able to form the beams in a second direction of space, orthogonal to the first direction.

In the example shown on the figure 2 , the hybrid beamformer includes Ny quasi-optical beamformers 101, 102, ..., 10i, ..., 10Ny, stacked one above the other, and Nx electron beam formers 201, ... , 20Nx, where Nx and Ny are integers greater than one. For example, on the figure 3 , Ny is equal to four and on the figure 5 , Nx and Ny are equal to two.

As shown on figures 2 , 3 and 4 each quasi-optical beamformer comprises a parallel plate guide (waveguide 10) consisting of two parallel metal plates 11, 12, spaced apart from one another, a lens 13 integrated in the waveguide 10, between the two metal plates, My internal horns 141, 142, ..., 14k, ... 14My, distributed periodically side by side along a focal axis of the lens 13, where My is greater than or equal to 2, My beam access ports 161, 162, ..., 16k, ... 16My, respectively associated with My internal horns and connected to a first end of the waveguide 10 and a linear radiating aperture 15 arranged at a second end of the waveguide 10. The linear aperture 15 may be associated with a linear horn or a radome common to all the quasi-optical beamformers of the hybrid beamformer. The quasi-optical beamforming apparatus makes it possible to focus, in the first direction of the space, the signals received by the linear radiating aperture 15, on the My beam access ports 161, 162, ..., 16k, ... 16My, depending on the direction of arrival of these received signals. The first direction of the space is parallel to the plane of the metal plates 11, 12 of the waveguides of the quasi-optical beam formers. The lens 13 may be an optical lens distributed over a large part of the volume of the parallel plate waveguide 10, such as, for example, of the Rotman lens type or of the index gradient lens type, for example a Luneberg lens. . Alternatively, the lens 13 may be a delay gradient metal lens located in a limited area of the parallel plate waveguide, as shown for example by the lens 13 illustrated in FIG. figure 2 and on the figure 4 , which extends transversely in an area of the waveguide located in front of the linear aperture 15. The quasi-optical beamformer may furthermore comprise a focusing device, for example a parabolic reflector, integrated transversely into the waveguide. wave 10, between the two parallel plates. In this case the quasi-optical beamformer has a structure conventionally called pillbox.

Each electron beam trainer 201,..., 20Nx comprises Ny input ports respectively connected to Ny quasi-optical beamformers 101, 102,..., 10i,..., 10Ny, each electron beam formatter 201 , ..., 20Nx having Mx outputs capable of delivering Mx different beams, where Mx is greater than or equal to one. Each electron beamformer 201, ..., 20Nx is connected to a selected beam access port of each of the quasi-optical beamformers Ny and applies to the signals from the corresponding beam access ports Ny a phase and amplitude control, then electronically recombines the Ny signals delivered by said beam access port of each of the Ny quasi-optical beamformers to form Mx beams according to the second direction of the orthogonal space in the first direction . To achieve the interconnection between each of the My beam access ports of the quasi-optical beam forming trainers and the N x electron beam trainers, it is necessary that the number of beam access ports My of each beam trainer quasi -optic equals the number Nx of electron beam trainers. The electron beam formation is reconfigurable by changing the phase and amplitude law applied to each beam access port of the quasi-optical beamformers. The electron beam formers allow reconfiguration, in the second direction of space, of the beams formed in the first direction by quasi-optical beamformers.

Compared to a conventional electron beamformer on a two-dimensional array of radiating elements, this hybrid beamforming considerably reduces the number of signals on which phase and amplitude control must be applied, since each electron beam trainer, the phase and amplitude control only relates to Ny beam access ports from each of the Ny quasi-optical beamformers instead of Nx '* Ny' radiating elements. a network of two-dimensional radiating elements, where N x 'would be the number of radiating elements along a first axis X and Ny' would be the number of radiating elements along a second axis Y.

The example of figure 5 illustrates a simplified block diagram, in reception, of an exemplary hybrid beamformer in which only two quasi-optical beamformers and two electron beamformers are shown and in which only one beam is outputted from each trainer of the beamformers. electron beams. In this for example, each electron beamformer 201, ..., 20Nx comprises a planar combination device 34, for example a candlestick-type combiner, capable of operating, receiving, power combining, and Ny phase control chains. and of amplitude 221, ..., 22Ny respectively connected to inputs of the combination device 34 to form the beams at the output of the combination device 34. The Ny phase and amplitude control chains 221, ..., 22Ny of each electron beamformer are respectively connected to a corresponding beam port 161, ..., 16Ny of each quasi-optical beamformer 101, ..., 10Ny. This electron beam trainer is therefore particularly simple and feasible because it comprises only combinations of Ny signals delivered on Ny beam access ports Ny trainers of quasi-optical beams. Each phase and amplitude control chain 221,..., 22Ny comprises in series, a filter 30 connected to a port for accessing beams 16i,..., 16Ny of a quasi-optical beamformer 101 , ..., 10Ny, an amplifier 31, as well as a variable attenuator 33 and a variable phase shifter 32 for applying a phase and amplitude control to the signals coming from the corresponding beam access port of each of the Ny quasi-optical beamformers. On the figure 5 there is only one beam formed at the output of the combination device 34, but depending on the desired application, it is of course possible to form several beams using more complex combination / division devices or trainers. of quasi-optical beams in SIW technology (in English: Substrate Integrated Waveguide) realized in the form of printed circuit boards (in English: Printed Circuit Board) as illustrated for example on the embodiments of figures 10 and 11 described below.

The quasi-optical beamformer has the advantage of operating in a very wide frequency band because it propagates the propagation mode TEM (Transverse Electro Magnetic) which is non-dispersive in frequencies. It can therefore be used to propagate signals in two sub-bands of very separate frequencies, such as Tx transmission and reception bands Rx in the Ka and Ku bands. In this case, in order to produce a transmitting and receiving antenna, the invention furthermore consists, in each quasi-optical beamformer, of arranging separate transmit and receive ports Tx and Rx, respectively dedicated to the transmission Tx and to the reception Rx, and to provide each port Tx, Rx with respective filters respectively centered on the transmission and reception frequency bands for separate the transmit and receive signals. The figure 6a represents an example of arrangement of two 16k1 transmission and 16k2 reception ports at the end of a waveguide 10 of a quasi-optical beamformer. On this figure 6a , the two ports Tx, Rx are provided with corresponding filters 181, 182 and the waveguide is provided with an enlarged end for housing the two ports Tx and Rx stacked one above the other. The two distinct ports Tx, Rx can be associated with separate horns internal to the quasi-optical beamformer. The physical size of the opening of the internal horns is different for the two transmitting and receiving frequency subbands so that the same size is normalized by the central wavelength corresponding to each frequency sub-band. . By way of nonlimiting example, for operation in the Ka band, in which the central reception frequency Rx is equal to 30 GHz and the central transmission frequency Tx is equal to 20 GHz, it is possible to have a first row of three receiving horns 14k2 side by side along the focal axis of the lens of the quasi-optical beamformer and in the same footprint, to arrange a second row of two 14k1 transmit horns side by side along of the focal axis of the quasi-optical beamformer lens, as shown by the two features illustrated in FIG. figure 6b the first and second rows being stacked inside the waveguide 10 with parallel plates. In this configuration, the beams produced at the Tx emission and at the Rx reception overlap at the same level and there are 3/2 times more reception beams Rx than emission beams Tx on the same angular sector covered by the quasi-optical beamformer.

When the transmitting and receiving frequency subbands are very separated from one another, there may be appearance of grating lobes during electron beam formation. This problem is due to the opening width at the output of the quasi-optical beamformer's linear horns, which must have an opening whose maximum size corresponds to a fraction of the wavelength and which are not therefore not suitable for operation in the two sub-bands of different frequencies Rx, Tx when they are very far apart. In order to optimally size the linear radiating openings of each quasi-optical beamformer, the invention may furthermore consist in eliminating linear horns and replacing them with a single, partially reflective radome common to all quasi-beamformers. -optics, and connected to all the linear radiating openings of the quasi-optical beamformers, as shown in the example of the figure 7 which concerns the case of the networking of three quasi-optical beamformers. On this figure 7 the radome 70 has a first partially reflective surface 71 sized for the receiving frequency subband and a second partially reflecting surface 72 sized for the transmit frequency subband. The two partially reflecting surfaces are respectively arranged at the output of the linear radiating openings of the different quasi-optical beam formers at a distance corresponding to the respective central wavelength of the two frequency sub-bands. The two reflecting surfaces distribute the radiofrequency signals, respectively in Rx reception and Tx transmission. In order to obtain the same directivity in reception and in emission, at the exit of the two reflecting surfaces, the radiating openings are of different widths for the two frequency sub-bands Rx and Tx, the radiating emission opening being larger than the radiating opening in reception.

In addition, the architecture of the antenna may be different depending on whether the operation is transmitting or receiving. In particular, on the example of figure 7 only two out of three quasi-optical beamformers have two beam access ports equipped with respective filters 181, 182 and thus operate in the two subbands Rx, Tx. The intermediate quasi-optical beamformer has only one beam access port equipped with a filter 182 dedicated to the reception and therefore operates only in the sub-band Rx. This intermediate quasi-optical beamformer comprises a second filter 182 housed in the linear radiating aperture 15 in order to select, at the corresponding linear radiating aperture, only the reception band.

Different applications are possible. The hybrid beamformer of the invention may be used in an antenna for a user terminal requiring delivery of a slave beam on a satellite. To reduce the cost of this application, it is particularly interesting that the antenna operates Tx transmission and Rx reception. An example of architecture of such an antenna is shown on the figure 8a . Only two quasi-optical beamformers 101, 102 are illustrated, but there can be many more than two. In this example, the hybrid beamformer comprises at least two quasi-optical beamformers common to the Tx transmission and the Rx reception, two separate specific electron beam formers, respectively dedicated to the emission 201, and to the 203, and switches 211, 212, 231, 232 having different positions respectively able to select, depending on their position, a port of access of several beams, the selectively connecting switches, the electronic beamformer 201, 203 dedicated to transmitting, respectively on reception, to one of the transmitting or receiving ports of each quasi-optical beamformer 101, 102 of the hybrid beamformer. The quasi-optical beamformer, common to the Tx emission and to the Rx reception, preforms the beams according to the first direction of the space, the two specific electron beam formers 201, 203, respectively dedicated to the emission and at the reception, form the beams according to the second direction of the space, orthogonal to the first direction. On the figure 8a each specific electronic beamformer 201, 203 comprises two amplitude control and amplitude control chains 221, 222, 242, 243 respectively dedicated to the two quasi-optical beamformers 101, 102, each phase and current control chain. amplitude being selectively connected, via a multi-position switch 211, 212, 231, 232, to a selected beam port of the respective quasi-optical beamformer. Each switch has an input connected to a phase and amplitude control chain of an electron beamformer and several outputs respectively connected to different respective ports of the various internal horns of a corresponding quasi-optical beamformer.

The beams preformed by the quasi-optical beamformer and delivered on the different beam access ports of the quasi-optical beamformer have orientation directions different from each other. Therefore, the beam pointing direction generated by the hybrid beamformer may be selected, depending on the switch position, by selecting one of several of the optical-to-optical beamformer ports.

The access ports, selected by the switches in all the stacked quasi-optical beam formers and connected to the same electron beam trainer, can have an identical orientation direction and cover an identical geographical area. In this case, the hybrid beamformer points in the geographical area covered by the corresponding access ports of each quasi-optical beamformer. Since, for each quasi-optical beamformer, the geographical areas covered by two adjacent access ports overlap with attenuations of between 3 dB and 6 dB, the hybrid beamformer will also exhibit attenuation of the same beam. order of magnitude in the two corresponding directions. To improve the gain of the antenna including the hybrid beamformer, it is possible to point a beam in an intermediate direction between two adjacent geographical areas. For this, the invention consists in alternating the access ports selected in different successive quasi-optical beam formers so that a first part of the selected access ports covers a first geographical area and a second part of the ports of access. Selected access covers a second geographic area, adjacent to the first geographical area. The number of access ports selected in each of the two adjacent geographic areas, depends on the desired intermediate pointing direction for the corresponding beam. The figure 8b illustrates an example of intermediate pointing of the beam located between two adjacent beams. In this figure 8b , the two ellipses 81, 82 represented in dotted lines represent the two beams generated in a first direction of space, by two adjacent quasi-optical beam formers and the three circles 83, 84, 85 in solid lines represent the beams delivered. at the output of the hybrid beamformer, after electron beam formation in the second direction of space, orthogonal to the first direction. Each of the two outer circles 83, 84 is obtained by selecting, for the two quasi-optical beam formers, access ports covering a first geographic area, respectively a second geographic area adjacent to the first geographic area. The two outer circles therefore correspond to two adjacent geographical areas. The intermediate circle 85 located between the two outer circles 83, 84 is obtained by selecting, for a first half, the access ports covering the first geographical area and, for a second half, access ports covering the second geographical area. adjacent to the first geographic area.

Furthermore, in the case where a large misalignment is desired, at this misalignment of the beam by selecting the ports of the quasi-optical beamformer, it is possible to add a mechanical misalignment of the quasi-optical beamformer to position the beam. quasi-optical beamformer in the right direction and thus reduce the complexity of electron beam formation.

The hybrid beamformer of the invention can also be used in a transmit and receive multibeam antenna as shown in the antenna example of FIG. figure 9 in the case where the spots cover a predetermined geographical area. In this example, the quasi-optical beam formers are identical to those described in connection with the figure 8a . Only the number of specific electron beam trainers dedicated to transmission and reception is increased according to the number of beams to be developed. On the figure 9 , two beams are developed on the show and two beams are developed at the reception. For each beam to be developed, if the quasi-optical beamformer has Ny stages, with Ny equal to two on the example of the figure 8a the electron beam trainer comprises Ny phase and amplitude control chains, each phase and amplitude control channel dedicated to the transmission, respectively to the reception, being selectively connected, via a switch to several different positions, for example four positions on the figure 9 at a chosen port of a respective quasi-optical beamformer, the ports being able to to be selected at the sending, respectively at the reception, by a first switch being different from the ports that can be selected on transmission, respectively on reception, by a second switch. In the case of an application for which it is necessary to perform any pointing from any of the ports of the quasi-optical beamformer, the selection of ports will be greater and the switches will be much more complex . The more complex the port selection, the more power losses there are. To mask the power losses, it is then possible to add amplifiers distributed between the switches of the quasi-optical beamformer.

In another application to a multibeam antenna mounted aboard a satellite of a constellation of satellites traveling in low or medium orbit, it is necessary to be able to make any pointing of the antenna from any beam access ports of quasi-optical beamformers. In this case, several beams must be formed at the output of each electron beam trainer. For this, as represented for example on the figure 10 each phase and amplitude control chain 221, 222 connected to the quasi-optical beamformers may include a bypass 52 for splitting the phase and amplitude control chain into a plurality of different channels 221a, 221b, 222a , 222b, each channel having a phase shifter 50a, 50b, 51a, 51b dedicated. This allows different phase shifts to be assigned to each beam access port of a quasi-optical beamformer. At the output of the phase shifters, a power combiner / divider recombines the channels so as to deliver several different beams Fa, Fb corresponding to different phase laws. On the example of the figure 10 two beams are delivered at the output of each electron beamformer, but of course this is not limiting, using a number of channels greater than two, it is possible to form a number of beams greater than two.

Alternatively, as shown on the figure 11 to achieve multiple beams at the output of each electron beamformer, each electron beamformer may include a quasi-optical 60 PCB-based formatter having a plurality of beam outputs corresponding to different phase shifts and a plurality of inputs to which the active channels are connected. 221, 222. The quasi-optical beamformer in PCB technology is then used in place of the signal combiner / divider shown on the figure 8 .

In both embodiments shown on the figures 10 and 11 , the beams thus obtained are then inclined only according to the phase shift applied on each channel. In the case of figure 10 the beams formed are independent of each other and can be pointed in any direction. In the case of figure 11 a cluster of beams is produced, and this cluster is orientable and the beams are not independent of each other.

The quasi-optical beam formers can be mounted with their longitudinal axis oriented parallel to the orthogonal axis of the satellite to preform a row of beams along this orthogonal axis and to recombine the ports of these quasi-optical beam formers with the electron beam trainer. This makes it possible to follow the same geographical area on the ground during the scrolling of the satellite and also allows detaching all the beams formed along the axis of scrolling when the satellite scrolls over a low traffic area, such as oceans.

Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims (10)

Active antenna architecture with reconfigurable beam formation, characterized in that it comprises a hybrid beamformer consisting on the one hand, Ny stacked planar quasi-optical beam formers, where Ny is an integer greater than one, each quasi-optical beamformer comprising a waveguide (10) with parallel plates (11, 12) having two ends respectively provided with a linear aperture (15) and My beam access ports (161, 162, ..., 16k, ... 16My), a lens (13) integrated in the parallel plate waveguide , internal horns (141, 142, ..., 14k, ... 14My) periodically distributed side by side along a focal axis of the lens (13), the beam access ports (161, 162 , ..., 16k, ... 16My) being respectively associated with internal horns (141, 142, ..., 14k, ... 14My), each quasi-optical beamformer being able to form beams in two separate frequency bands, respectively transmission and reception, in a first direction of the space parallel to the plane of the parallel plate waveguides, And on the other hand, at least one planar electronic beamformer (201, 202, 203, ... 20Nx) comprising Ny phase and amplitude control strings and a combination device (34) comprising Ny inputs respectively connected to the Ny chains phase and amplitude control and at least one beam output each phase and amplitude control chain being connected to a respective beam access port of each quasi-optical beamformer, the electron beamformer being able to form beams in a second direction of space, orthogonal to the first direction. Antenna architecture according to claim 1, characterized in that it further comprises switches (211, 212, 231, 232) capable of selecting, in each quasi-optical beamformer, a port among all the ports of access of available beams, each switch having an input connected to a phase and amplitude control channel of the electron beamformer and several outputs respectively connected to a plurality of respective beam access ports of the corresponding quasi-optical beamformer. Antenna architecture according to one of claims 1 or 2, characterized in that the beam access ports (161, 162, ..., 16k, ... 16M) consist of a first row of ports transmitters (16k1) arranged side by side along the focal axis of the lens (13) and a second row of receiving ports (16k2) arranged side by side along the focal axis of the lens (13), the first and second rows being stacked one above the other, the transmit ports (16k1) and the receive ports (16k2) being distinct and of different sizes, each port of emission, respectively receiving, being provided with a respective filter (181, 182) centered on the transmission frequency band, respectively receiving. Antenna architecture according to one of Claims 1 to 3, characterized in that the linear radiating openings (15) of the different quasi-optical beam formers are connected in a network to a single, partially reflective radome (70) common to all the quasi-optical beam formers, the radome (70) having a first partially reflecting surface (71) sized for the receiving frequency sub-band and a second partially reflecting surface (72) sized for the sub-frequency band. the first and second partially reflective surfaces being respectively arranged at the output of the linear radiating openings, at a distance corresponding to a respective central wavelength of the two transmission and reception frequency subbands. Antenna architecture according to one of Claims 3 or 4, characterized in that the hybrid beamformer comprises a quasi-optical beamformer (101, 102) common to the Tx transmission and to the Rx receiver, two trainers separate specific electron beams (201, 203) respectively dedicated to transmission and reception and switches (211, 212, 231, 232) having different positions respectively capable of selecting a port of access of several beams, each switch selectively connecting, according to its position, a phase control and amplitude control channel of the electronic beamformer dedicated to the transmission, respectively to the reception, to one of the transmission or receiving ports, respectively each trainer of quasi-optical beams. Antenna architecture according to claim 5, characterized in that the beam access ports, selected by the switches in all the stacked quasi-optical beam formers and connected to the same electron beamformer, have a direction of rotation. identical orientation and cover an identical geographical area. Antenna architecture according to claim 5, characterized in that a first portion of the beam access ports selected by the switches in the stacked quasi-optical beam formers covers a first geographic area and a second portion of the ports. Beam accesses, selected by the switches in the stacked quasi-optical beamformers, cover a second geographic area adjacent to the first geographic area. Antenna architecture according to one of claims 1 to 5, characterized in that the combination device (34) consists of a combiner / divider having Nx inputs respectively connected to the Nx phase and amplitude control strings and a beam output. Antenna architecture according to one of claims 1 to 5, characterized in that the combining device (34) has a shunt (52) for splitting each phase and amplitude control chain into a plurality of different paths (221a). , 221b, 222a, 222b), each channel having a dedicated phase shifter (50a, 50b, 51a, 51b). Antenna architecture according to one of Claims 1 to 5, characterized in that the combination device (34) is constituted by a quasi-optical beamformator in PCB technology comprising Nx inputs respectively connected to the Nx phase control chains. and amplitude and several beam outputs.

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